import math
class cYuan:
    name=None
    color=None
    _r=0
    def show(self):
        print(self.name,self.color,self._r)
    def sYuan(self,r):
        
        s=math.pi*(self._r**2)
        print("圆的面积：%f"%s)
    def lYuan(self,r):
        
        l=math.pi*(self._r**2)
        print("圆的周长：%f"%l)
car1=cYuan(10,10,"green",10)
car1.show()
car1._r(20.0)


